Abstract

Background: Exercise-induced bronchoconstriction (EIB) and vocal cord dysfunction (VCD) are frequent causes of exercise-induced dyspnea. The two entities can coexist, which is difficult to differentiate and manage properly.

Aim: To identify risk factors for EIB, VCD and their combination from patients' gender, history and pulmonary function tests.

Methods: We performed a two year retrospective analysis of patients referred to our tertiary pulmonary centre because of respiratory complaints on exercise. They underwent exercise bronchial provocation testing. EIB was defined as ≥10% fall in %FEV1 from the pre-exercise level. VCD was diagnosed if exercise-induced inspiratory stridor was observed by a physician, or visualised by flexible laringoscopy during exercise testing. Sex, atopy, positive family history for asthma, %FEV1 and vital capacity (VC) were used as predictor variables in logistic regression model to assess the odds ratio (OR) for EIB, VCD and their combination.

Results: Records from 79 patients (64.6% girls), mean age 15.4 yrs. (SD 2.3) were included. Atopy was present in 55.7% of patients and positive family history for asthma in 36.7%. Mean %FEV1 was 104.3 (SD 14.6) and mean VC 98.0% (SD 13.1%). The model for VCD showed significant relationships for sex (p=.019, girls having 9.3 times higher odds for VCD), VC (p=.04, OR 1.1), and %FEV1 (p=.005, OR 0.9). The models for EIB and for EIB with VCD combined showed no significant relationship with predictor variables.

Conclusion: EIB is best diagnosed with exercise testing. For VCD, our data show potential predicting value of gender and results of pulmonary function tests.